A vehicle equipped with an internal combustion engine runs with power generated by the internal combustion engine. This vehicle is equipped with a storage battery (battery) and electric auxiliaries, in addition to the internal combustion engine. The internal combustion engine is started with the electric power supplied from the storage battery. The electric auxiliaries operate with the electric power supplied from the storage battery. The electric auxiliaries include, for example, various control devices, an electronic control fuel injection device, an actuator for transmission control and an electric power assisted steering.
As is known, the vehicle equipped with the internal combustion engine performs idle reduction to reduce idling of the internal combustion engine for the purpose of saving the fuel consumption and reducing the emission gas. Idle reduction is also expressed as idle stop, idling stop, engine stop at vehicle stop or no idling. Idle reduction control for controlling idle reduction (stop start control) includes a stop control of stopping the internal combustion engine according to the driving condition of the vehicle and a restart control of restarting the internal combustion engine that has been stopped by the stop control.
Patent Literature 1 describes idle reduction control to determine whether the stop control is feasible, based on the voltage of the storage battery detected during a stop period of the internal combustion engine. Patent Literature 2 describes idle reduction control to determine whether the stop control is feasible, based on the voltage of the storage battery detected on the occasion of restart of the internal combustion engine by the restart control.